This study, which is ancillary to the Multiple Risk Factor Intervention Trial, is recording the ultralow frequency ballistocardiograms (ULF Bcg) of men randomized to usual care and special care groups of MRFIT. The capacity of the ULF Bcg to predict future CHD in this high risk group will be studied. In addition, the effects of intervention on the ULF Bcg will be examined in detail.